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Mechanical engineering

Application of the directive 94/9/EC to Safe Openings

Safe Openings - Annex II, 1.2.6

Annex II, Essential requirement 1.2.6 reads as follows:

1.2.6. Safe opening

If equipment and protective systems are in a housing or a locked container forming part of the explosion protection itself, it must be possible to open such housing or container only with a special tool or by means of appropriate protection measures.

Even though there is now only "special fastenings", the three historic levels of "safe opening" are not precluded by the essential requirement 1.2.6 and it is not the intention of directive 94/9/EC to require a level of safety higher than that required by the third editions of EN 50014 series of standards for the equivalent zone of risk.

Level 1, the use of "Special Tools" e.g. on fasteners with hexagonal socket heads can still be used as specifically described by 1.2.6.

Level 2, the use of fasteners which require some form of tool to open the door e.g. a simple screwdriver, an adjustable spanner, or a key, are allowed in 1.2.6 where the additional "appropriate protection measure" would be the presence of a warning label requiring the operator to "De-energise before opening" or similar text.

Note : To qualify for Level 2 a "key" operated fastener (if used) should be used in conjunction with a lock mechanism that automatically locks the door in the closed position when the door is closed. The use of a lock which requires the use of a key to lock it in the closed position is not allowed for Level 2 since the operator may choose not to lock the door again when the door is closed and the additional protection required is no longer provided.

Level 3, the use of a door fastener which would allow the operator to open the door of the enclosure without the use of any tool i.e. with the "bare hands", is also not prevented by 1.2.6. However because of the increased personal and explosion risk additional measures have to be applied e.g. the use of an electrical or mechanical interlock to de-energise automatically the interior of the enclosure as well as the conspicuous presence of the warning label used in Level 2 above.

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